Technical Field
The present disclosure generally relates to a technique for controlling a projection image.
Description of the Related Art
Digital signages for presenting an advertisement, guidance information, and the like may have been widespread as a new information medium. Some digital signages may project a video on a wall or the like without using a display panel. In some instances, there may be an information display method using a projector, for presenting different images between a person viewing an image through glasses and a person viewing an image with the naked eyes. Further, in the method, a main image with a compressed gradation value may be projected on a screen through a first polarization filter, and a correction image corresponding to a difference between gradation values of a sub image with a changed gradation value and gradation values of the main image may be projected on the screen through a second polarization filter with polarization components different from those of the first polarization filter.
According to the method, each viewer may adopt a viewing method according to preferable one of the images (whether to use glasses) to view the preferable one of the images. However, when the screen on which the images are projected is fixed as in the method, each viewer may need to move to a position where the screen can be visually recognized and may need to face the direction of the screen.